In a joint, the range of motion depends upon the anatomy and condition of that joint and on the particular genetics of each individual. Many joints primarily move either in flexion or extension, although some joints also are capable of rotational movement in varying degrees. Flexion is to bend the joint and extension is to straighten the joint; however, in the orthopedic convention some joints only flex. Some joints, such as the knee, may exhibit a slight internal or external rotation during flexion or extension.
Most people do not appreciate the complexity of joint motion until something goes wrong, such as when an injury results in lost range of motion. When a joint is injured, either by trauma or by surgery, scar tissue can form or tissue can contract and consequently limit the range of motion of the joint. For example, adhesions can form between tissues and the muscle can contract itself with permanent muscle contracture or tissue hypertrophy such as capsular tissue or skin tissue. Lost range of motion may also result from trauma such as exposure to extreme temperatures, chemical burns, or surgical trauma so that tissue planes which normally glide across each other may become adhered together to markedly restrict motion. The adhered tissues may result from chemical bonds, tissue hypertrophy, proteins such as Actin or Myosin in the tissue, or simply from bleeding and immobilization. It is often possible to mediate, and possibly even correct this condition by use of a range-of-motion (ROM) orthosis, but the longer the period of stiffness or loss of motion the greater the time interval and the force required to regain lost range of motion. Therefore, it is beneficial to treat the tissue or joint as early as possible. For example, a ROM orthosis may be applied immediately after surgery or as soon as the stiffness problem is diagnosed.
ROM orthoses are devices commonly used during physical rehabilitative therapy to increase the range-of-motion over which the patient can flex or extend the joint. Commercially available ROM orthoses are typically attached on opposite members of the joint and apply a torque to rotate the joint in opposition to the contraction. The force is gradually increased to increase the working range or angle of joint motion. Exemplary orthoses include U.S. Pat. No. 6,921,377 (“Finger Orthosis”), U.S. Pat. No. 6,770,047 (“Method of using a neck brace”), U.S. Pat. No. 6,599,263 (“Shoulder Orthosis”), U.S. Pat. No. 6,113,562 (“Shoulder Orthosis”), U.S. Pat. No. 6,503,213 (“Method of using a neck brace”), U.S. Pat. No. 6,502,577 (“Finger Orthosis”), U.S. Pat. No. 5,848,979 (“Orthosis”), U.S. Pat. No. 5,685,830 (“Adjustable Orthosis Having One-Piece Connector Section for Flexing”), U.S. Pat. No. 5,611,764 (“Method of Increasing Range of Motion”), U.S. Pat. No. 5,503,619 (“Orthosis for Bending Wrists”), U.S. Pat. No. 5,456,268 (“Adjustable Orthosis”), U.S. Pat. No. 5,453,075 (“Orthosis with Distraction through Range of Motion”), U.S. Pat. No. 5,395,303 (“Orthosis with Distraction through Range of Motion”), U.S. Pat. No. 5,365,947 (“Adjustable Orthosis”), U.S. Pat. No. 5,285,773 (“Orthosis with Distraction through Range of Motion”), U.S. Pat. No. 5,213,095 (“Orthosis with Joint Distraction”), and U.S. Pat. No. 5,167,612 (“Adjustable Orthosis”), and U.S. Publication No. 20040215111 (“Patient monitoring apparatus and method for orthosis and other devices”), all to Bonutti and herein are expressly incorporated by reference in their entirety.
In the past, many ROM orthothes required manual operation, may not have been capable of accurately simulating the natural range of motion of a healthy joint, or may not have allowed for easy adjustment of the treatment protocol (e.g., force applied, range of motion exercised, duration of treatment, etc.).